Ceramic honeycomb body structures are widely used both in the thermal regenerators of waste air cleaning installations and for regenerating process air. Various ceramic honeycomb bodies are known, for instance from EP 0 472 605 B1, which are used as heat accumulator compounds in regenerators in waste gas treatment installations. These honeycomb bodies are typically disposed in stacks, and at least two honeycomb bodies are aligned with their channels in the direction of the respective gas flow, optionally spaced apart from one another.
The known heat accumulator compounds are ceramic honeycomb bodies which are embodied substantially prismatically, which have channels parallel to the primary prism axis with intersecting, essentially equal channel cross sections, and which have a specific surface area between 200 and 3000 m2/m3 and a hydraulic diameter between 1 and 12 mm.
Because of the aligned arrangement of the prismatic honeycomb bodies, and in particular of their channels, the flow profile of the cross section of the heat storage chamber continues throughout all the layers of the stack. Even in zones in which there is little or no flow in a layer oriented toward the inflow side of the gas, there is a flow in the same way as in the preceding layer, because of the aligned arrangement of the channels as their course continues. The same is true for zones and channels with a strong flow through them. The continuation of the flow profile through the heat storage chamber layers is accordingly due essentially to the aligned arrangement of the channels or prisms and to a virtually continuous laminar flow.
To achieve the greatest possible thermal efficiency with a simultaneously low pressure loss, regenerator beds are often designed with very large bed cross sections. However, the theoretically high degrees of heat recovery sought can be achieved only with the highest possible degree of utilization of the available heat accumulator compound. A high degree of utilization is equated among other things with the most uniform possible oncoming flow and/or a homogeneous flow distribution over the bed cross section. Large bed cross sections, unfavorable valve or flap positions, and overly low pressure losses over the regenerator bed make this goal harder to achieve. Often, bed cross sections are specified, since existing installations with low-efficiency heat storage materials and a high pressure loss (such as bulk material packing) are involved. Therefore, a substitution of more-efficient honeycomb bodies and a low pressure loss is sought. The theoretical heat recovery values are in practice often not achieved then, because as a result of the low pressure loss and/or the unfavorable oncoming flow conditions, a homogeneous flow through the regenerator bed cannot be attained, and zones with a high flow through them as well as zones with little or no flow through them develop in the regenerator bed. The zones with a low flow through them make hardly any contribution to heat recovery, and the theoretical total efficiency is accordingly not attained because of the poor flow distribution.
As a result of the present noncommunicating channel structure in ceramic honeycomb bodies, air flows inside a honeycomb body are unable to mix or be distributed. Stacking the ceramic honeycomb bodies on flat bases does not allow any transverse flow between the layers.
By the use of honeycomb bodies with structured end face geometries (for instance as in Austrian Patent Document AT 412 817 B), significant improvements in the transverse flow within a regenerator bed can be attained; however, attaining the desired effects requires multiple layers of structured honeycomb bodies, and zones in the inlet region and in the middle region of the regenerator bed exhibit flow deficits.